Put vs Patch

HTTP (Hypertext Transfer Protocol) is the foundation of data communication on the internet. It specifies the way information is exchanged between a client (such as a web browser) and a server. Among the various HTTP methods, two commonly used methods for updating resources on a server are PUT and PATCH. Although they both serve the purpose of modifying resources, they differ significantly in their usage and semantics. In this essay, we will delve into the differences between the PUT and PATCH HTTP methods.

PUT Method:

The PUT method is primarily used to update or create a resource at a specific URI (Uniform Resource Identifier). When a client sends a PUT request to a server, it instructs the server to store the enclosed entity at the provided URI. If the resource does not exist at the given URI, the server creates a new resource with the provided data. If the resource already exists, the server replaces it with the updated data.

Key characteristics of the PUT method include:

1. Idempotency: PUT requests are idempotent, meaning that performing the same PUT request multiple times has the same effect as a single request. This property is crucial for network reliability because it ensures that even if a request is duplicated or retried, the state of the server remains unchanged.

2. Complete Replacement: PUT requests typically involve sending the entire resource representation to the server. This means that when a client sends a PUT request, it must include all the data necessary to represent the resource in its entirety. The server then replaces the existing resource with the new representation provided in the request payload.

3. Resource URI: PUT requests are targeted at a specific URI, indicating where the resource should be created or updated. The client explicitly specifies the URI in the request, making it clear to the server where the operation should be performed.

4. Lack of Partial Updates: Unlike the PATCH method, PUT does not support partial updates. When a client sends a PUT request, it replaces the entire resource at the specified URI. This makes PUT suitable for scenarios where complete replacement is desired, such as uploading a new version of a file.

PATCH Method:

The PATCH method is used to apply partial modifications to a resource. Instead of replacing the entire resource, a PATCH request typically contains instructions on how to modify specific parts of the resource. This makes PATCH more efficient than PUT in scenarios where only a portion of the resource needs to be updated.

Key characteristics of the PATCH method include:

1. Partial Updates: PATCH requests are designed for partial updates, allowing clients to modify specific fields or properties of a resource without affecting the rest of the resource's state. This enables more granular control over resource modifications and can be particularly useful for large or complex resources where updating the entire representation is impractical.

2. Idempotency Consideration: While PATCH requests can be designed to be idempotent, it's not a strict requirement like it is for PUT requests. Implementations of PATCH vary, and some may result in different outcomes when applied multiple times, depending on how the server handles the partial updates.

3. Resource URI: Similar to the PUT method, PATCH requests are also targeted at a specific URI, indicating the location of the resource to be modified. The client specifies the URI in the request, just as it does with PUT requests.

4. Payload Format: PATCH requests typically include a payload that describes the modifications to be applied to the resource. This payload can take various forms, such as JSON Patch, JSON Merge Patch, or XML Patch, depending on the application's requirements and the format supported by the server.

Differences and Use Cases:

Now, let's explore the key differences between the PUT and PATCH methods and their respective use cases:

1. Granularity of Updates:

- PUT: Designed for complete replacement of a resource. It requires sending the entire representation of the resource with each request.

- PATCH: Intended for partial updates, allowing clients to modify specific fields or properties of a resource without replacing the entire representation.

2. Efficiency:

- PUT: Less efficient when only a small portion of the resource needs to be updated, as it requires sending the entire representation.

- PATCH: More efficient for partial updates, especially with large or complex resources, as it only requires sending the modified fields.

3. Idempotency:

- PUT: Strictly requires idempotent behavior, meaning that repeating the same request has the same effect as a single request.

- PATCH: While idempotency is desirable, it's not strictly required. Implementations may vary in their idempotent behavior.

4. Error Handling:

- PUT: Errors during a PUT request may result in inconsistencies if the entire resource fails to update properly.

- PATCH: Errors during a PATCH request are typically more localized, affecting only the fields being modified. This can make error handling and recovery more manageable.

5. Use Cases:

- PUT: Suitable for scenarios where complete replacement of a resource is desired, such as uploading a new version of a file or replacing an entire object in a database.

- PATCH: Ideal for scenarios where only specific fields or properties of a resource need to be updated, such as updating user profile information or modifying configuration settings.

### Conclusion:

In summary, while both the PUT and PATCH methods serve the purpose of modifying resources on a server, they differ significantly in their approach and use cases. PUT is designed for complete replacement of resources and requires sending the entire representation, making it suitable for scenarios where full updates are needed. On the other hand, PATCH is intended for partial updates, allowing clients to modify specific fields or properties of a resource without replacing the entire representation, which can be more efficient for large or complex resources. Understanding the differences between PUT and PATCH is essential for designing robust and efficient APIs that meet the requirements of various application scenarios.